Call me "professor."

I've just taken a position on the faculty of Cogswell College in Sunnyvale, California--in the heart of Silicon Valley. I'm teaching five classes in 3-D modeling and animation to a fantastic group of students. These guys are so typical of today's emerging 3-D artists. Intensely motivated, thrilled to be involved in this new medium, and above all, strongly independent learners. It's hard to keep up with them.

Cogswell is offering a B.A. in Computer and Video Imaging, with a very heavy emphasis on 3-D. This is the first such specialized degree that I'm aware of, but I'm sure that they must be quickly cropping up at other institutions. The field is simply exploding, and the number of students in the Cogswell program has increased 50 percent for the past semester alone. There is a rush to get involved, and I encourage everyone with a serious interest to make the leap as soon as possible. For the next few years, there will undoubtedly be far more demand for qualified 3-D artists and animators than supply. And as bandwidth problems on the internet are solved and the Web becomes a video medium, opportunities for the 3-D artist will expand immeasurably beyond the present film, broadcast and multimedia industries. Cogswell's website is at www.cogswell.edu. Or contact me directly, using the "comments" links on this site if you'd like more information.

We're going to finish up with our photorealistic still-life this time, focusing on the hardest part--the glass beaker.

Here, for a final time, is the finished scene.

We've been taking all along about identifying those surfacing parameters that are most important to selling a single surface. With the apples it is was the diffuse color, with specularity being a significant, but secondary, factor. The metal spoon relied mostly on reflection. The key to the lemon was bump mapping. Take a look back at the last few lessons if you don't remember these points.

It's easy, of course, to point to transparency as the key parameter of a glass surface material. Glass is transparent, and the more transparent, the better the glass. But if an object is really transparent, why do we see it at all? This is the main question to consider when surfacing glass.

Here is an isolated shot of the beaker without the purple liquid.

Notice from the start how much more convincing the material was in the entire scene. This is a simple fact of perception. As part of the larger scene, with the emotional atmosphere of the lighting, and particularly with the distraction of the colorful apples, the viewer does not dwell so critically on the glass object. Once the beaker alone is isolated, its weaknesses begin to appear. Highly realistic surfaces can be very difficult to create, and even when possible, may demand an unreasonable amount of experimentation time. Just as with the spoon, my judgment was that, under the circumstances of the scene, the surfacing of the beaker was "good enough." But isolated like this, the computer origins of the image are more evident.

But back to our question. If the object is transparent, how do we see it?